Sample Replication of Periphyton Collected from Artificial Substrates

Extensive use of and field experiments with a commercially available artificial substrate sampling device suggest limited reproducibility of data, which may or may not be peculiar to this specific device under certain conditions. Use of a coefficient of similarity to compare diatomaceous species associations between replicate samples on glass slides indicated that similarity of at least 70 percent between replicates was common. Replicated side-by-side experiments under natural conditions indicated statistically significant between-sampler differences of biomasses and chlorophyll yields. Within-sampler variation among replicate slides was inconsistent, but usually in the range of 20 to 30 percent; however, these differences were not consistent with slide positions. A direct relationship of surface velocity to biomass and chlorophyll yield was revealed, although this was probably also related to solar incidence. The data indicate the necessity to understand the limits and effective variables regulating periphyton growth on artificial substrates. Significant differences in periphyton yields may reflect inappropriate sampler placement or sampler effects rather than effects of water quality.